1,2,5-Thiadiazole-3,4-dicarbonitrile 1 reacts with copper powder in a
closed vessel and in an inert atmosphere to form the corresponding cop
per porphyrazine 2a in fair fields. A similar reaction of 1 with magne
sium powder gives about equal amounts of unchanged 1 and the triazine
3. Low yields of the magnesium porphyrazine 2b were obtained from reac
tions of 1 with magnesium alcoholates in either 1-propanol or methanol
. The required oxidation of sulfur from S(II) in 1 to S(IV) in the por
phyrazines 2, and stereoelectronic requirements around the nitrile fun
ctions of 1, might explain the reluctant formation of compounds 2.